Add exporters & instrumentation for otel-cpp to registry.

[lalitb]

Preview: https://deploy-preview-892--opentelemetry.netlify.app/registry/?s=&component=all&language=cpp#

[chalin]

The language field value should be cpp, per

opentelemetry.io/layouts/registry/list.html

Line 6 in fa565be

{{ $languages.Set "cpp" "C++" -}}

Otherwise, these entries don't show up in the registry as you can see this PR's preview https://deploy-preview-892--opentelemetry.netlify.app/registry/?s=&component=all&language=cpp#

[chalin]

Let me know if you'd like me to make the changes @lalitb.

[lalitb]

Let me know if you'd like me to make the changes @lalitb.

Thanks @chalin if you can do so, else I will take it during my morning.

[chalin]

Thanks @chalin if you can do so, else I will take it during my morning.

I'm on it.

[chalin]

Apologies for the extra comments that have appeared: I was trying to edit the PR via github.dev, but it wouldn't let me commit the changes, so I fall back to editing each file individually (the only way I could get the changes in without submitting a new PR).

[chalin]

Language fields updated